// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_PROPERTY_DETAILS_H_
#define V8_PROPERTY_DETAILS_H_

#include "include/v8.h"
#include "src/allocation.h"
// TODO(ishell): remove once FLAG_track_constant_fields is removed.
#include "src/flags.h"
#include "src/utils.h"

namespace v8 {
namespace internal {

    // ES6 6.1.7.1
    enum PropertyAttributes {
        NONE = ::v8::None,
        READ_ONLY = ::v8::ReadOnly,
        DONT_ENUM = ::v8::DontEnum,
        DONT_DELETE = ::v8::DontDelete,

        ALL_ATTRIBUTES_MASK = READ_ONLY | DONT_ENUM | DONT_DELETE,

        SEALED = DONT_DELETE,
        FROZEN = SEALED | READ_ONLY,

        ABSENT = 64, // Used in runtime to indicate a property is absent.
        // ABSENT can never be stored in or returned from a descriptor's attributes
        // bitfield.  It is only used as a return value meaning the attributes of
        // a non-existent property.
    };

    enum PropertyFilter {
        ALL_PROPERTIES = 0,
        ONLY_WRITABLE = 1,
        ONLY_ENUMERABLE = 2,
        ONLY_CONFIGURABLE = 4,
        SKIP_STRINGS = 8,
        SKIP_SYMBOLS = 16,
        ONLY_ALL_CAN_READ = 32,
        PRIVATE_NAMES_ONLY = 64,
        ENUMERABLE_STRINGS = ONLY_ENUMERABLE | SKIP_SYMBOLS,
    };
    // Enable fast comparisons of PropertyAttributes against PropertyFilters.
    STATIC_ASSERT(ALL_PROPERTIES == static_cast<PropertyFilter>(NONE));
    STATIC_ASSERT(ONLY_WRITABLE == static_cast<PropertyFilter>(READ_ONLY));
    STATIC_ASSERT(ONLY_ENUMERABLE == static_cast<PropertyFilter>(DONT_ENUM));
    STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>(DONT_DELETE));
    STATIC_ASSERT(((SKIP_STRINGS | SKIP_SYMBOLS | ONLY_ALL_CAN_READ) & ALL_ATTRIBUTES_MASK) == 0);
    STATIC_ASSERT(ALL_PROPERTIES == static_cast<PropertyFilter>(v8::PropertyFilter::ALL_PROPERTIES));
    STATIC_ASSERT(ONLY_WRITABLE == static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_WRITABLE));
    STATIC_ASSERT(ONLY_ENUMERABLE == static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_ENUMERABLE));
    STATIC_ASSERT(ONLY_CONFIGURABLE == static_cast<PropertyFilter>(v8::PropertyFilter::ONLY_CONFIGURABLE));
    STATIC_ASSERT(SKIP_STRINGS == static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_STRINGS));
    STATIC_ASSERT(SKIP_SYMBOLS == static_cast<PropertyFilter>(v8::PropertyFilter::SKIP_SYMBOLS));

    class Smi;
    class TypeInfo;

    // Order of kinds is significant.
    // Must fit in the BitField PropertyDetails::KindField.
    enum PropertyKind { kData = 0,
        kAccessor = 1 };

    // Order of modes is significant.
    // Must fit in the BitField PropertyDetails::LocationField.
    enum PropertyLocation { kField = 0,
        kDescriptor = 1 };

    // Order of modes is significant.
    // Must fit in the BitField PropertyDetails::ConstnessField.
    enum class PropertyConstness { kMutable = 0,
        kConst = 1 };

    // TODO(ishell): remove once constant field tracking is done.
    const PropertyConstness kDefaultFieldConstness = FLAG_track_constant_fields ? PropertyConstness::kConst
                                                                                : PropertyConstness::kMutable;

    class Representation {
    public:
        enum Kind {
            kNone,
            kSmi,
            kDouble,
            kHeapObject,
            kTagged,
            kNumRepresentations
        };

        Representation()
            : kind_(kNone)
        {
        }

        static Representation None() { return Representation(kNone); }
        static Representation Tagged() { return Representation(kTagged); }
        static Representation Smi() { return Representation(kSmi); }
        static Representation Double() { return Representation(kDouble); }
        static Representation HeapObject() { return Representation(kHeapObject); }

        static Representation FromKind(Kind kind) { return Representation(kind); }

        bool Equals(const Representation& other) const
        {
            return kind_ == other.kind_;
        }

        bool IsCompatibleForLoad(const Representation& other) const
        {
            return IsDouble() == other.IsDouble();
        }

        bool IsCompatibleForStore(const Representation& other) const
        {
            return Equals(other);
        }

        bool CanBeInPlaceChangedTo(const Representation& other) const
        {
            if (IsNone())
                return true;
            if (!FLAG_modify_field_representation_inplace)
                return false;
            return (IsSmi() || IsHeapObject()) && other.IsTagged();
        }

        bool is_more_general_than(const Representation& other) const
        {
            if (IsHeapObject())
                return other.IsNone();
            return kind_ > other.kind_;
        }

        bool fits_into(const Representation& other) const
        {
            return other.is_more_general_than(*this) || other.Equals(*this);
        }

        Representation generalize(Representation other)
        {
            if (other.fits_into(*this))
                return *this;
            if (other.is_more_general_than(*this))
                return other;
            return Representation::Tagged();
        }

        int size() const
        {
            DCHECK(!IsNone());
            if (IsDouble())
                return kDoubleSize;
            DCHECK(IsTagged() || IsSmi() || IsHeapObject());
            return kTaggedSize;
        }

        Kind kind() const { return static_cast<Kind>(kind_); }
        bool IsNone() const { return kind_ == kNone; }
        bool IsTagged() const { return kind_ == kTagged; }
        bool IsSmi() const { return kind_ == kSmi; }
        bool IsSmiOrTagged() const { return IsSmi() || IsTagged(); }
        bool IsDouble() const { return kind_ == kDouble; }
        bool IsHeapObject() const { return kind_ == kHeapObject; }

        const char* Mnemonic() const
        {
            switch (kind_) {
            case kNone:
                return "v";
            case kTagged:
                return "t";
            case kSmi:
                return "s";
            case kDouble:
                return "d";
            case kHeapObject:
                return "h";
            }
            UNREACHABLE();
        }

    private:
        explicit Representation(Kind k)
            : kind_(k)
        {
        }

        // Make sure kind fits in int8.
        STATIC_ASSERT(kNumRepresentations <= (1 << kBitsPerByte));

        int8_t kind_;
    };

    static const int kDescriptorIndexBitCount = 10;
    static const int kFirstInobjectPropertyOffsetBitCount = 7;
    // The maximum number of descriptors we want in a descriptor array.  It should
    // fit in a page and also the following should hold:
    // kMaxNumberOfDescriptors + kFieldsAdded <= PropertyArray::kMaxLength.
    static const int kMaxNumberOfDescriptors = (1 << kDescriptorIndexBitCount) - 4;
    static const int kInvalidEnumCacheSentinel = (1 << kDescriptorIndexBitCount) - 1;

    enum class PropertyCellType {
        // Meaningful when a property cell does not contain the hole.
        kUndefined, // The PREMONOMORPHIC of property cells.
        kConstant, // Cell has been assigned only once.
        kConstantType, // Cell has been assigned only one type.
        kMutable, // Cell will no longer be tracked as constant.

        // Meaningful when a property cell contains the hole.
        kUninitialized = kUndefined, // Cell has never been initialized.
        kInvalidated = kConstant, // Cell has been deleted, invalidated or never
        // existed.

        // For dictionaries not holding cells.
        kNoCell = kMutable,
    };

    enum class PropertyCellConstantType {
        kSmi,
        kStableMap,
    };

    // PropertyDetails captures type and attributes for a property.
    // They are used both in property dictionaries and instance descriptors.
    class PropertyDetails {
    public:
        // Property details for dictionary mode properties/elements.
        PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
            PropertyCellType cell_type, int dictionary_index = 0)
        {
            value_ = KindField::encode(kind) | LocationField::encode(kField) | AttributesField::encode(attributes) | DictionaryStorageField::encode(dictionary_index) | PropertyCellTypeField::encode(cell_type);
        }

        // Property details for fast mode properties.
        PropertyDetails(PropertyKind kind, PropertyAttributes attributes,
            PropertyLocation location, PropertyConstness constness,
            Representation representation, int field_index = 0)
        {
            value_ = KindField::encode(kind) | AttributesField::encode(attributes) | LocationField::encode(location) | ConstnessField::encode(constness) | RepresentationField::encode(EncodeRepresentation(representation)) | FieldIndexField::encode(field_index);
        }

        static PropertyDetails Empty(
            PropertyCellType cell_type = PropertyCellType::kNoCell)
        {
            return PropertyDetails(kData, NONE, cell_type);
        }

        int pointer() const { return DescriptorPointer::decode(value_); }

        uint32_t get_value() const
        {
            return value_;
        }

        PropertyDetails set_pointer(int i) const
        {
            return PropertyDetails(value_, i);
        }

        PropertyDetails set_cell_type(PropertyCellType type) const
        {
            PropertyDetails details = *this;
            details.value_ = PropertyCellTypeField::update(details.value_, type);
            return details;
        }

        PropertyDetails set_index(int index) const
        {
            PropertyDetails details = *this;
            details.value_ = DictionaryStorageField::update(details.value_, index);
            return details;
        }

        PropertyDetails CopyWithRepresentation(Representation representation) const
        {
            return PropertyDetails(value_, representation);
        }
        PropertyDetails CopyWithConstness(PropertyConstness constness) const
        {
            return PropertyDetails(value_, constness);
        }
        PropertyDetails CopyAddAttributes(PropertyAttributes new_attributes) const
        {
            new_attributes = static_cast<PropertyAttributes>(attributes() | new_attributes);
            return PropertyDetails(value_, new_attributes);
        }

        // Conversion for storing details as Object.
        explicit inline PropertyDetails(Smi smi);
        inline Smi AsSmi() const;

        static uint8_t EncodeRepresentation(Representation representation)
        {
            return representation.kind();
        }

        static Representation DecodeRepresentation(uint32_t bits)
        {
            return Representation::FromKind(static_cast<Representation::Kind>(bits));
        }

        PropertyKind kind() const { return KindField::decode(value_); }
        PropertyLocation location() const { return LocationField::decode(value_); }
        PropertyConstness constness() const { return ConstnessField::decode(value_); }

        PropertyAttributes attributes() const
        {
            return AttributesField::decode(value_);
        }

        bool HasKindAndAttributes(PropertyKind kind, PropertyAttributes attributes)
        {
            return (value_ & (KindField::kMask | AttributesField::kMask)) == (KindField::encode(kind) | AttributesField::encode(attributes));
        }

        int dictionary_index() const
        {
            return DictionaryStorageField::decode(value_);
        }

        Representation representation() const
        {
            return DecodeRepresentation(RepresentationField::decode(value_));
        }

        int field_index() const { return FieldIndexField::decode(value_); }

        inline int field_width_in_words() const;

        static bool IsValidIndex(int index)
        {
            return DictionaryStorageField::is_valid(index);
        }

        bool IsReadOnly() const { return (attributes() & READ_ONLY) != 0; }
        bool IsConfigurable() const { return (attributes() & DONT_DELETE) == 0; }
        bool IsDontEnum() const { return (attributes() & DONT_ENUM) != 0; }
        bool IsEnumerable() const { return !IsDontEnum(); }
        PropertyCellType cell_type() const
        {
            return PropertyCellTypeField::decode(value_);
        }

        // Bit fields in value_ (type, shift, size). Must be public so the
        // constants can be embedded in generated code.
        class KindField : public BitField<PropertyKind, 0, 1> {
        };
        class LocationField : public BitField<PropertyLocation, KindField::kNext, 1> {
        };
        class ConstnessField
            : public BitField<PropertyConstness, LocationField::kNext, 1> {
        };
        class AttributesField
            : public BitField<PropertyAttributes, ConstnessField::kNext, 3> {
        };
        static const int kAttributesReadOnlyMask = (READ_ONLY << AttributesField::kShift);
        static const int kAttributesDontDeleteMask = (DONT_DELETE << AttributesField::kShift);
        static const int kAttributesDontEnumMask = (DONT_ENUM << AttributesField::kShift);

        // Bit fields for normalized objects.
        class PropertyCellTypeField
            : public BitField<PropertyCellType, AttributesField::kNext, 2> {
        };
        class DictionaryStorageField
            : public BitField<uint32_t, PropertyCellTypeField::kNext, 23> {
        };

        // Bit fields for fast objects.
        class RepresentationField
            : public BitField<uint32_t, AttributesField::kNext, 3> {
        };
        class DescriptorPointer
            : public BitField<uint32_t, RepresentationField::kNext,
                  kDescriptorIndexBitCount> {
        }; // NOLINT
        class FieldIndexField : public BitField<uint32_t, DescriptorPointer::kNext,
                                    kDescriptorIndexBitCount> {
        }; // NOLINT

        // All bits for both fast and slow objects must fit in a smi.
        STATIC_ASSERT(DictionaryStorageField::kNext <= 31);
        STATIC_ASSERT(FieldIndexField::kNext <= 31);

        static const int kInitialIndex = 1;

#ifdef OBJECT_PRINT
        // For our gdb macros, we should perhaps change these in the future.
        void Print(bool dictionary_mode);
#endif

        enum PrintMode {
            kPrintAttributes = 1 << 0,
            kPrintFieldIndex = 1 << 1,
            kPrintRepresentation = 1 << 2,
            kPrintPointer = 1 << 3,

            kForProperties = kPrintFieldIndex,
            kForTransitions = kPrintAttributes,
            kPrintFull = -1,
        };
        void PrintAsSlowTo(std::ostream& out);
        void PrintAsFastTo(std::ostream& out, PrintMode mode = kPrintFull);

    private:
        PropertyDetails(int value, int pointer)
        {
            value_ = DescriptorPointer::update(value, pointer);
        }
        PropertyDetails(int value, Representation representation)
        {
            value_ = RepresentationField::update(
                value, EncodeRepresentation(representation));
        }
        PropertyDetails(int value, PropertyConstness constness)
        {
            value_ = ConstnessField::update(value, constness);
        }
        PropertyDetails(int value, PropertyAttributes attributes)
        {
            value_ = AttributesField::update(value, attributes);
        }

        uint32_t value_;
    };

    // kField location is more general than kDescriptor, kDescriptor generalizes
    // only to itself.
    inline bool IsGeneralizableTo(PropertyLocation a, PropertyLocation b)
    {
        return b == kField || a == kDescriptor;
    }

    // PropertyConstness::kMutable constness is more general than
    // VariableMode::kConst, VariableMode::kConst generalizes only to itself.
    inline bool IsGeneralizableTo(PropertyConstness a, PropertyConstness b)
    {
        return b == PropertyConstness::kMutable || a == PropertyConstness::kConst;
    }

    inline PropertyConstness GeneralizeConstness(PropertyConstness a,
        PropertyConstness b)
    {
        return a == PropertyConstness::kMutable ? PropertyConstness::kMutable : b;
    }

    V8_EXPORT_PRIVATE std::ostream& operator<<(
        std::ostream& os, const PropertyAttributes& attributes);
} // namespace internal
} // namespace v8

#endif // V8_PROPERTY_DETAILS_H_
